What's huge and solid stone and about 380 million years old?

You may not know if you haven't been to Zhangjiajie in Hunan province, but local officials there are eager to spread the word about Yangjiajie and its stunning peak walls carved from mountains by nature over the millennia.

Part of the UNESCO World Heritage Site Wulingyuan Scenic and Historic Interest Area, Yangjiajie boasts about a dozen of the immense parallel walls of varying heights. Ongoing tourism development projects will be completed in March, local tourism officials said at a recent press conference at Diaoyutai State Guesthouse in Beijing.